The invention relates to a hand-held turret drill. This type of drill generally comprises a casing and a driving spindle rotatably journaled in the casing for rotating a driven spindle during operation. The driven spindle is in an operatable position in which it is coaxially flush with the driving spindle. The drill includes a driving motor for directly or indirectly rotating the driving spindle and a coupling for connecting and disconnecting the engagement of the driven spindle with the driving spindle. The drill also includes a turret head that is revolvably mounted on the casing and is provided with at least two driven spindles. The turret head is arranged in such a way that the spindles can be rotated one by one into the operatable position. A first coupling part of the coupling is made on the end of the driven spindle that faces the driving spindle, while an opposite second coupling part is connected to the driving spindle in a non-rotatable manner and is axially movable between a connected and disconnected position in relation to this driving spindle. The drill further includes means for manually moving the second coupling part between its connected and disconnected positions.
Generally, hand-held drills have chucks for clamping a rotary tool. In many cases, such a drill is employed for jobs that require consecutive use of various tools which therefore must be clamped one by one into the chuck.
An example of such a job is one that simply consists in screwing a wood screw into a piece of wood. When a conventional drill with one spindle is employed for this purpose, the following operations are required.
A drill bit is clamped in the chuck while the drill is inoperative. A hole is predrilled in the wood by actuating the drill. The drill is dwelled and the drill bit removed from the hole. The chuck is opened and the drill bit is removed from the chuck. A screw bit is then clamped in the chuck instead and the screw is screwed into the predrilled hole by reactuating the drill.
If the job only comprises a single or a small number of screws, it is still manageable to employ a drill with only one operatable spindle despite the many operations. However, this is not the case if the job comprises many screws. Then, the many tool changes will really be an inconvenience to the operator just as they will take up a considerable part of the total time spent on doing the job.
Attempts have been made at trying to solve this problem. One attempt includes providing a hand-held drill with several driven spindles which one at the time are coupled into operative engagement with the driving spindle of the drill. Each of the driven spindles then has a chuck that provides a a tool that does not require change as long as the same kind of work is done repeatedly. Thereby, many tool changes are saved.
Such a drill is known from U.S. Pat. No. 5,573,358. In this patent, there are two driven spindles both journaled in a revolvable arrangement of bearings which can bring either one of the driven spindles into operative engagement with the drive shaft of the drill upon turning. During such a turning manoeuvre, the driven spindles will travel in a large curve. Thereby, the structure with the projecting spindles and their chucks will become unstable in itself. The revolvable arrangement of bearings must be supported by a guideway, but as the spindle with the tool that is not in use at the moment is hanging out to the side, the drill becomes lopsided and unwieldy as well as difficult to operate in narrow spaces, e.g. in a corner. When changing between the two driven spindles, the revolvable arrangement of bearings is turned back and forth in relation to the rest of the drill. This known structure is relatively complex, is hard to manage, is difficult to employ and has a limited operating range.
Thus, there is a need for an improved drill that remedies the problems of the art. The present invention now addresses this need and provides one solution to these problems.
The invention relates to a hand-held drill of the type described above. The drill generally comprises a casing; a driven spindle; a driving spindle rotatably journaled in the casing for engaging and rotating the driven spindle during operation, with the driven spindle being in an operatable position in which it is coaxially flush with the driving spindle; a driving motor for directly or indirectly rotating the driving spindle; a coupling for connecting and disconnecting engagement of the driven spindle with the driving spindle, with the coupling including a first coupling part made on the end of the driven spindle that is facing the driving spindle, and an opposite second coupling part non-rotatably connected to the driving spindle and axially movable between a connected and disconnected position in relation to the driving spindle; a turret head revolvably mounted on the casing and provided with at least two driven spindles with the turret head arranged in such a way that the spindles can be rotated one by one into an operatable position with the driven spindle; and means for manually displacing the second coupling part between its connected and disconnected positions. This drill preferably includes a guideway mounted in the casing and extending parallel to the axis of the driving spindle; and a slide movably received in the guideway and having a through channel extending coaxially with the driving spindle, whereby the second coupling part rotatably extends through the slide channel and is secured therein against axial movement.
The drill may also include a lock having a first locking part on the turret head for each driven spindle and a second locking part on the slide, with the second locking part being arranged to engage in a locking manner with one of the first locking parts when the corresponding driven spindle is in the operatable position and the first and second coupling part are coupled together. The lock generally may include a locking pawl on the slide and a notch in the turret head for each driven spindle, or a locking pawl on the turret head for each driven spindle and a recess in the slide.
The means for manually moving the second coupling part between its connected and disconnected position generally comprises a movable member associated with the second coupling part or with the slide. This member preferably comprises at least one finger knob that extends out through the casing.
The second coupling part may be a coupling bar extending in an axially movable but non-rotatable manner into an axially extending end hole in the driving spindle and extending in a rotatable manner but secured against axial movement through the slide channel. The second coupling part preferably comprises a bushing journaled in a rotatable manner but secured against axial movement in the channel of the slide and a coupling bar extending into or through the bushing in a non-rotatable manner and secured against axial movement and into an axially extending end hole in the driving spindle in a non-rotatable and movable manner.
The drill preferably includes at least one biasing member for affecting the slide with a force acting in direction towards the driven spindle. A convenient biasing member is a coupling spring that provides spring power against the slide.
In another embodiment, the drill comprises a base for supporting the drill on a supporting face, wherein a portion of the base is arranged to be moved between a retracted position of use and an advanced position of support.